Process for cold forming a metal tube with an inwardly thickened end

ABSTRACT

Placing a short tubular metal blank into an open die, having an inner, annular extrusion shoulder, and partially pressing the blank through the shoulder to extrude an elongated, uniform wall thickness tube portion. Then placing a second blank into the die in end to end contact with the remaining portion of the first blank, and pressing the second blank similarly part way through the die extrusion shoulder to simultaneously extrude the remaining portion of the first blank through the shoulder to form it with the same OD as its first extruded portion, but with a smaller ID, to form an inwardly thickened end portion on the extruded part, while also extruding the uniform wall thickness portion on the second blank, and then repeating the cycle.

United States Patent Simon June 3, 1975 PROCESS FOR COLD FORMING A METALTUBE WITH AN INWARDLY THICKENED END [76] Inventor: Joseph A. Simon, 8620Mt. Elliott, Grosse Pointe Farms, Mich. 4821] [22] Filed: July I, 197421 Appl. No.: 484,423

Related U.S. Application Data [62] Division of Ser. No. 384,44l, Aug. 1,1973, Pat. No.

6/1974 Katunich 29/4703 Primary Examiner-C. W. Lanham AssistantExaminerRobert M. Rogers Attorney, Agent, or FirmCullen, Settle, Sloman& Cantor [57] ABSTRACT Placing a short tubular metal blank into an opendie, having an inner, annular extrusion shoulder, and partially pressingthe blank through the shoulder to extrude an elongated, uniform wallthickness tube portion. Then placing a second blank into the die in endto end contact with the remaining portion of the first blank, andpressing the second blank similarly part way through the die extrusionshoulder to simultaneously extrude the remaining portion of the firstblank through the shoulder to form it with the same OD as its firstextruded portion, but with a smaller ID, to form an inwardly thickenedend portion on the extruded part, while also extruding the uniform wallthickness portion on the second blank, and then repeating the cycle.

2 Claims, 8 Drawing Figures PROCESS FOR COLD FORMING A METAL TUBE WITHAN INWARDLY THICKENED END BACKGROUND OF THE INVENTION The inventionherein relates to a process for cold forming or extruding a metal tubehaving a thickened or inwardly flanged end. While the process herein maybe used to form tubes for a variety of purposes, it is particularlyadaptable in the manufacture of rear axles for trucks, such as iscommonly called a Salesbury axle". In such type axles, it is common toforge or machine or both, an elongated tube having an end portion ofreduced outer and inner diameters and formed with steps or shoulders forconnection to wheel bearings and the like. The main portion of the axleis formed as a relatively thin wall uniform diameter tube and theopposite end is formed with an inwardly directed flange or thickenedportion. Such end is normally inserted into a socket formed on ahousing, such as a truck differential housing.

The forming of such a type axle requires a number of forging steps andthen a number of machining steps to provide the accurate sizes requiredand also proper surface finishings. Since the axle is made of one pieceof metal, a number of compromises as to the type of metal selected andthe proper heat treating, must be made to maximize the differentstrength and other characteristics required from the opposite ends ofthe axle.

Hence, the process herein is concerned with the manufacturing of part ofsuch a type axle, namely, the body or barrel portion with the thickenedend, wherein such an axle may be made in two parts rather than in one asis conventional, to thereby reduce manufacturing steps and costs andprovide for a better product. Such process may also be used to producemetal parts which generally are uniformly tubular in shape with aninwardly extending flange or thickened portion at one end.

SUMMARY OF THE INVENTION The invention herein contemplates forming auniform crosssection tube with an inwardly directed flange or thickenedportion at one end, starting with a short, tubular blank which is coldformed or extruded through a die in a press. The die, mounted upon apress bed, is formed with an open blank receiving portion, beneath whichis an annular shoulder or extrusion throat with a smaller openingthrough which the blank may be extruded. The press ram is provided witha ram punch member for pressing the blank through the shoulder and itsopening.

The process herein includes first pressing the blank partially throughthe extrusion shoulder so that a substantial portion of the blank isextruded into a uniform, relatively thin wall, tubular section, leavingan outwardly flanged remaining blank portion in the die blank receivingpart. Then a new blank is placed into the die and it too is presseddownwardly through the shoulder or die opening. In so doing, theprevious, partially pressed blank is pushed through the extrusionshoulder. As it goes through, its thickened outwardly directed flangeportion cold flows inwardly to form an inwardly thickened or flangedportion.

Meanwhile, the new blank is partially extruded and takes the place ofthe preceding blank. Then the cycle is repeated by again adding a newblank, etc. Thus, each new blank acts as if it is part of the ram punch,

making the contact with the preceding blank and consequently permittingmuch faster production as compared to a single blank by blank operation,but also reducing wear and breakage of the ram punch itself.

The ram punch may be provided with properly sized, smaller extensionmembers which fit into the blank for sizing the inner diameters of theblank during the extrusion thereof. Hence, the finished product can beheld to a very accurate tolerance with respect to its OD and ID, therebyeliminating machining and surface finishing steps which have beenrequired in the past, in connection with forming such devices by forgingor machining processes.

Where the finished product is to be used as a portion of the abovementioned Salesbury type axle, the axle portion containing the variousstepped configurations and the like, may be separately made, as forexample, by the process described in my prior U.S. Pat. No. 3,739,620,issued June 19, 1973 for a Process for Forming a Flared End TubularMetal Part.

The two separate pieces, namely, the piece made by the invention of thisapplication and the second piece may then be welded together such as bymeans of inserting the end of one into the other and spinning one piecerelative to the other to generate sufficient friction and heat for agood spin formed weld. In this way, a finished axle or similar devicemay be made, with the advantage that the two pieces may be separatelymade of separate types of metal and/or separately heat treated tothereby improve the desired strength and characteristics of each endportion of the finished part.

These and other objects and advantages of this invention will becomeapparent upon reading the following description, of which the attacheddrawings form a part.

DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view of a truck axlemade in accordance with the invention herein.

FIG. 2 is a view similar to FIG. 1 but shows the two parts of the axleseparated.

FIG. 3 illustrates in cross-section, the press apparatus for carrying.out the process herein, with the ram opened and a blank ready forinsertion into the die.

FIG. 4 schematically illustrates the position of the blank in the diewith the ram moved downwardly.

FIGS. 5-8 show successive steps in the process.

DETAILED DESCRIPTION FIGS. 1 and 2 illustrate a hollow, tubular axle l0,commonly referred to as a Salesbury axle" and typically used as the rearaxle of a light truck. Such axles typically are formed with a reduced orconfigured end portion 11 having various diametrical portions forreceiving and engaging with wheel or bearing parts, and an elongatedtubular central or barrel portion 12 having an inwardly flared orinwardly thickened end portion 13. Such axles have in the past beenmanufactured in one piece through a variety of forging and/or machiningoperations.

The process herein contemplates forming the axle in two separate pieces,namely, a first piece 15 which encompasses the reduced end portion 11,and a second piece 16 which includes the barrel portion 12 and thethickened portion 13. Thus, the two pieces are separately made with thepiece 16 made in accordance with the process of this application and thepiece 15 made by some other process. To assemble the two pieces to makea complete axle, their respective ends 17 and 18 may be abutted andwelded together by a suitable conventional welding processes.

The process herein contemplates maing the piece 16, or similarly shapedpieces, from a metal blank 20 which is in the form of a short, tubularpiece of metal, such as steel. As shown in FIG. 3, the manufacturingequipment includes a die 21 mounted upon a press bed 22 of a conventionpress. The die has an upwardly opening blank reciving chamber or portion23, beneath which is an annular extrusion should 24 to provide a centralextrusion opening throat 25, beneath which is a relieved exit endopening 26. An opening 17 in the bed or in blocks built up upon the bedprovides space for downward movement of the extrusion.

The die is aligned with a conventional press ram 30, which isschematically shown as the press itself forms no part of the inventionherein. The ram includes a downwardly extending press ram punch 31 sizedto fit into the die opening 23. The punch also includes a smallerdiameter, downwardly extending sizing punch 32 and a second, evensmaller diameter lower sizirg punch 33.

With reference to FIGS. 3 through 8, the process herein includes thefollowing steps: First, as shown in FIG. 3, a blank 20 is dropped intothe die opening 23. The press ram 30 is then lowered, as shown in FIG.4, so that the lower end of the ram punch 31 engages the upper end ofthe blank and the sizing punch 32 extends through the opening in thecenter of the blank. Next, as shown in FIG. 5, the ram is moveddownwardly against the press bed, to extrude the blank partially throughthe extrusion shoulder and its opening 25, thereby extruding arelatively thin wall, uniform diameter wall thickness tube or barrelportion 12.

The downward movement of the ram is stopped before the blank iscompletely extruded through the shoulder so as to leave an enlargementor outwardly extending flange portion 35 within the die opening 23, thisportion being the unextruded portion of the blank.

Next, the ram is retracted, i.e., lifted upwardly, and a new blank 20a,identical to the original blank 20 is dropped into the die opening 23,as seen in FIG. 6. The new blank is now in end to end contact with theupper end of the original blank 20, that is the remaining enlargedportion 35 thereof.

Thereafter, as shown in FIG. 7, the ram is again lowered to press theblank 20a downwardly into the die, which thereby presses the originalblank through the die opening completely. In this step, the materialwhich formed the remaining portion of the original blank, that is theenlargement 35, is forced inwardly, now being positioned in an inwardlydirected enlargement, namely, the thickened portion 13 whose ID is sizedby the sizing punch 33.

Meanwhile, the ram continues moving downwardly, as shown in FIG. 8, sothat the second blank 20a is extruded, in the same way as was the firstblank, and simultaneously pushes the completely extruded original piecedownwardly and out of the die completely. The press continues downwardlyuntil the second blank assumes the shape and position of the first blankas is illustrated in FIG. and thereafter a new blank is inserted asshown in FIG. 6 and the cycle repeats.

Hence, as can be seen, each blank functions as a portion of the ram topush the preceding blank during the 4 time it itself is being extruded.This permits rapid operation, as well as preserving the press equipmentand die against much of the normal wear which would be encountered in aone-by-one blank pressing operation.

Essentially, the process herein is carried out with the metal beingcold. Actually, it is preferable to heat the metal so as to warm it to apoint below its metallurgical transition points to thus permit easierflow of the metal under pressure and thereby reduce the required rarnpressure. Thus, by cold forming, it is meant that the blanl" are eitherat room temperature or at relatively low temperatures, i.e., belowtransition points.

Although the figures illustrate the extrusion of a tube of circularouter and inner diameters, the shape in cross-section of the tube may bevaried. In addition, it is possible in this process to form inner orouter surface configurations on the tube, such as longitudinallyextending gear teeth, by suitably profiling either the shoulder throator opening 25 or the surfaces of the sizing punches 32 and 33.

Having fully described an operative embodiment of this invention, I nowclaim:

1. A method for forming an elongated tubular metal axle-like part havingone end formed with reduced outer diameter portions and the opposite endformed with an inwardly thickened portion and a central barrel portionof uniform diameter and thickness, comprising:

separately forming the part in two separate pieces,

namely, one piece having the formed reduced outer diameter portions withthat piece terminating at the barrel portion, and a second piececonsisting of the barrel portion and the inwardly thickened portion,comprising extruding said second piece by:

positioning a relatively short tubular blank within a die mounted uponthe base of a press having an aligned ram, with the die having an openinlet end with a blank receiving portion and an outlet end having aninwardly extending annular extrusion shoulder whose innercross-sectional diameter is smaller than that of the blank receivingportion for Y extruding the blank therethrough;

ram pushing the blank partway through the die shoulder for therebyextruding the barrel portion on the blank, leaving the remaining portionof the blank still within the die blank receiving portion;

next, inserting a second, identical blank into the die blank receivingportion in end to end contact with the first mentioned blank;

then ram pushing the second blank through the die shoulder to form abarrel portion thereon, thereby simultaneously forcing the first blankcompletely through the die shoulder to cause the portion previouslyremaining within the die blank receiving portion to flow inwardly toform the inwardly thickened portion of the piece, and then repeating thecycle of inserting a new blank, etc.;

and thereafter welding said extruded second piece to a preformed firstpiece end to end, to form the completed axle-like part.

2. A method as defined in claim 1 and said welding comprising the stepsof inserting the edge of the unthickened end of the second piece intothe edge of the corresponding diameter end of the first piece and thenspinning one piece relative to the other to spin weld them together.

1. A method for forming an elongated tubular metal axle-like part havingone end formed with reduced outer diameter portions and the opposite endformed with an inwardly thickened portion and a central barrel portionof uniform diameter and thickness, comprising: separately forming thepart in two separate pieces, namely, one piece having the formed reducedouter diameter portions with that piece terminating at the barrelportion, and a second piece consisting of the barrel portion and theinwardly thickened portion, comprising extruding said second piece by:positioning a relatively short tubular blank within a die mounted uponthe base of a press having an aligned ram, with the die having an openinlet end with a blank receiving portion and an outlet end having aninwardly extending annular extrusion shoulder whose innercross-sectional diameter is smaller than that of the blank receivingportion for extruding the blank therethrough; ram pushing the blankpartway through the die shoulder for thereby extruding the barrelportion on the blank, leaving the remaining portion of the blank stillwithin the die blank receiving portion; next, inserting a second,identical blank into the die blank receiving portion in end to endcontact with the first mentioned blank; then ram pushing the secondblank through the die shoulder to form a barrel portion thereon, therebysimultaneously forcing the first blank completely through the dieshoulder to cause the portion previously remaining within the die blankreceiving portion to flow inwardly to form the inwardly thickenedportion of the piece, and then repeating the cycle of inserting a newblank, etc.; and thereafter welding said extruded second piece to apreformed first piece end to end, to form the completed axle-likepart.
 1. A method for forming an elongated tubular metal axle-like parthaving one end formed with reduced outer diameter portions and theopposite end formed with an inwardly thickened portion and a centralbarrel portion of uniform diameter and thickness, comprising: separatelyforming the part in two separate pieces, namely, one piece having theformed reduced outer diameter portions with that piece terminating atthe barrel portion, and a second piece consisting of the barrel portionand the inwardly thickened portion, comprising extruding said secondpiece by: positioning a relatively short tubular blank within a diemounted upon the base of a press having an aligned ram, with the diehaving an open inlet end with a blank receiving portion and an outletend having an inwardly extending annular extrusion shoulder whose innercross-sectional diameter is smaller than that of the blank receivingportion for extruding the blank therethrough; ram pushing the blankpartway through the die shoulder for thereby extruding the barrelportion on the blank, leaving the remaining portion of the blank stillwithin the die blank receiving portion; next, inserting a second,identical blank into the die blank receiving portion in end to endcontact with the first mentioned blank; then ram pushing the secondblank through the die shoulder to form a barrel portion thereon, therebysimultaneously forcing the first blank completely through the dieshoulder to cause the portion previously remaining within the die blankreceiving portion to flow inwardly to form the inwardly thickenedportion of the piece, and then repeating the cycle of inserting a newblank, etc.; and thereafter welding said extruded second piece to apreformed first piece end to end, to form the completed axle-like part.